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5 collectors have some rare collection，then comes the $$6^{th}$$ collector with 50 pieces of collection，and then the average piece of collection is 5 more than the average before. Then comes the $$7^{th}$$ collector with some collection，and the average is 5 more than the average of the first 6 collectors. How many pieces of collection does the $$7^{th}$$ collector have？

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